1. Field of the Invention
This invention relates generally to an electronic musical instrument and particularly to an automatic rhythm performing apparatus by which a plurality of rhythmic tones corresponding respectively to a plurality of rhythmic musical instruments are produced at a time.
2. Prior Art
There has been proposed a conventional automatic rhythm performing apparatus in which the total volume of a plurality of rhythmic tones produced at a time is varied by one control device such as a variable resistor. When performing music through a musical instrument with this conventional apparatus, the performer can vary the total volume of the rhythmic tones through the variable resistor. This conventional apparatus is disadvantageous however in that the volumes of the rhythmic tones are varied at the same rate when the total volume of the rhythmic tones is varied. This can worsen the musical balance of the respective rhythmic tones in certain kinds of rhythms to make the rhythmic tones sound odd.
According to experiment conducted by the inventor, Table 1 shows the optimum volume relationships of eight-beat rhythmic tones at specific total volume levels which tones comprise a high-hat cymbals tone (closed), a high-hat cymbals tone (open), a snare drum tone and a bass drum tone.
TABLE 1 ______________________________________ pp p mp mf f ff ______________________________________ High-hat cymbals (closed) 0 0 0 0 0 0 High-hat cymbals (open) -10 -4 -2 0 -2 0 Snare drum -10 -4 -4 0 0 +2 Bass drum -12 -4 -6 0 0 +4 ______________________________________ Wherein each value is expressed in dB.
In this table, the volume level of each of the four rhythmic tones at the total volume level of mezzo-forte (mf) is used as a reference for determining the volume levels of its corresponding rhythmic tone at the total volumes other than mezzo-forte. The volume level of each of the four rhythmic tones at each of the total volume levels other than mezzo-forte such as forte (f) and mezzo-piano (mp) is indicated in the corresponding column of this Table 1 in which the volume level of the closed high-hat cymbals tone is used as a reference.
It will be understood from this Table 1 that when the total volume is varied from mezzo-forte (mf) to forte (f), the volume level of the closed high-hat cymbals tone should be decreased by 2 dB in order to maintain the optimum volume relationship although the volume levels of the snare drum tone and the bass drum tone need not be varied. On the other hand, when the total volume is adjusted to fortissimo (ff), the volume levels of the snare drum tone and the bass drum tone should be increased by 2 dB and 4 dB, respectively.
As described above, the optimum volume relationship of the respective rhythmic tones is varied in accordance with the variation of the total volume thereof. Therefore, if the volumes of the rhythmic tones are varied only through one variable resistor for controlling the total volume thereof, the volume relationship of the rhythmic tones is worsened, so that the rhythmic tones generated sound odd.